Surgical clips are known which are designed to permanently or temporarily occlude body passageways, and may be used in procedures including the surgical closure of veins and arteries for haemiostasis; ligation; vascular occlusion; occlusion of congenital or aberrant cardiac vessels; the occlusion of body ducts for sterilisation or prior to resection; intracranial vessel occlusion for neurosurgery; occlusion of aberrant vessels or aneurysms; and occlusion of arterio-venous malformations. A general principle is that such clips close the body passageway by gripping, without puncturing the tissue.
Various designs of surgical clip are known, including the Hem-o-lok ligating clip available from Weck Closure Systems and the Yasargil-Phynox clip available from Aesculap. The Hem-o-lok clip has a hinged plastic jaw comprising two jaw members with cooperating snap-fit closure formations, and is applied by a simple pliers-like applicator which closes the open jaw members together across the blood vessel to be occluded. The Yasargil-Phynox clip has a hinged metal jaw with a self-closing bias. Application of this clip is performed using a simple pliers-like applier, by prising the jaw members apart across the blood vessel to be occluded and then releasing the applier so that the jaw members spring together.
In each of these cases, in order to actuate the loaded applier the surgeon must make available the whole of his dominant hand, because of the pliers-grip hand action required. Furthermore, in each case, each clip must be loaded onto the applier manually and individually in the open condition.
In WO-A-00/35355, the disclosure of which is incorporated herein by reference, there is disclosed surgical clips having first and second ends and an intermediate central portion. The ends are preferably legs which extend in generally the same direction in a first (open) configuration of the clip, to allow the body passageway to be received in the clip. The clip is constructed so that the ends can close towards the central portion under an inherent biassing force into a second (closed) configuration so that the body passageway is then gripped by the clip. The inherent biassing force can be provided by use of a temperature-dependent shape memory material for the construction of the clip, and by arranging for the clip to experience a temperature change when the change from the first to the second configuration is desired. This temperature change can be a rise in temperature as a result of the clip being introduced into an operating zone within a patient's body.
WO-A-00/35355 also discloses two applicators for applying the clips. One of these comprises a shaft for holding the clips, the shaft having a first, proximal end connected to a handle and trigger and a second, distal end provided with a port through which the clips are dispensed. The clips are held in sequence in the shaft and are advanced along the shaft towards the distal end by a spring biased pressing rod. The clips to be loaded into the applicator each comprise a central elongate element having two enlarged ends, forming a shape resembling that of a weightlifter's dumbbell. The clips are loaded end-to-end in the shaft of the applicator.
In use, the port of the applicator is positioned over the vessel to be occluded, and the clips are advanced along the shaft until the foremost clip is positioned over the vessel. Once the foremost clip is in contact with the vessel, the clip warms up to body temperature, and as it does so it deforms into its second configuration and encircles the vessel.
A second applicator disclosed in WO-A-00/35355 is generally similar, but the clips housed in the apparatus are maintained at a low temperature by a temperature control device.
More recently, I have modified the shape of the prior art surgical clip to improve the occlusion performance. A version of the modified clip is shown in FIG. 1 of the accompanying drawings. The present invention relates particularly, though not exclusively, to an applicator for applying surgical clips of this type.
Referring to FIG. 1, a clip 1 of this type is generally planar with a central (main) portion 2 and a pair of resilient limbs 3, 4 each extending from the central portion of the clip so that the free ends project in a generally similar forward direction. The stems of the limbs preferably extend in opposite lateral directions from the central portion and then curve round towards their free ends into the forward direction. The central portion of the clip comprises a base portion 5 and a reaction or counter-surface portion 6, the reaction portion being connected to the base portion 5 and defining a reaction surface 7. The reaction surface is preferably elongate, in the lateral direction, and is preferably substantially fixed in relation to the movement of the limbs from a first, open, configuration to a second, closed, configuration. The connection between the base portion and the reaction portion of the clip is preferably via a neck portion, which is preferably narrow in relation to at least the reaction portion.
The clip 1 is preferably generally planar but with the respective planes of the parts offset somewhat against one another. In particular, the plane of the reaction portion 6 may be at an angle (e.g. up to 30°) to the plane of the base portion 5, with a corresponding twist provided at the region of connection between the two portions. Preferably also, one limb 3 lies to one side of (e.g. above) the plane of the base portion, and the other limb 4 lies to the opposite side of (e.g. below) that plane.
FIG. 1 shows such a clip in its resting configuration at room temperature. In this configuration, the limbs can be splayed (stressed) apart to an open configuration within the maximum recoverable stress of the material, and a bias towards the closed condition can be provided, e.g. using shape-memory materials. When the clip is applied in its open configuration to a body passageway, from an applicator, the limbs 3, 4 of the clip move under an inherent biassing force from the open configuration to the closed configuration. In the closed configuration, the free ends 8, 9 of the limbs overlie each side of (above and below) the reaction portion 6, gripping the passageway to be occluded in the plane of the clip and thus providing an efficient and secure occlusive effect. In order to provide the necessary closing force, the clip is preferably made from a stress-dependent and/or temperature-dependent shape-memory material, such that the clip can be stored in the open configuration under a certain stress and at a temperature below body temperature, but will move to the closed configuration when the stress is released and/or the temperature raised (e.g. when introduced into an operating zone within a patient). A suitable material is nitinol.
As shown in FIG. 1, the base portion 5 of the clip is preferably constructed in a plurality of sections (e.g. two halves) mutually linked by one or more region of weakness which can easily be cut to release the clip from the body passageway after use.
For further details of the construction of this type of clip, please see my International (PCT) Patent Application No. PCT/GB2004/001060, the contents of which are incorporated herein by reference. I have found that the modified clip arrangement described and claimed in that PCT patent application and illustrated in FIG. 1 of the accompanying drawings provides a remarkable and useful gripping and occlusive action on a wide range of body passageways.
Previous applicators for clips of this general type, such as those of WO-A-00/35355 mentioned above, are not suitable for the particular improved clip arrangement described above.
It is an object of the present invention to provide an applicator whereby the clips in the improved arrangement described above can be held before use and then individually dispensed to close onto and occlude a body passageway in a controlled and simple manner by a surgeon.